The manganese cation disrupts membrane dynamics along the secretory pathway

The endoplasmic reticulum and Golgi apparatus play key roles in regulating the folding, assembly, and transport of newly synthesized proteins along th e secretory pathway. We find that the divalent cation manganese disrupts th e Golgi apparatus and endoplasmic reticulum (ER). The Golgi apparatus is fr agmented into smaller dispersed structures upon manganese treatment. Golgi residents, such as TGN46, beta 1,4-galactosyltransferase, giantin, and GM13 0, are still segregated and partitioned correctly into smaller stacked frag ments in manganese-treated cells. The mesh-like ER network is substantially affected and peripheral ER elements are collapsed. These effects are consi stent with manganese-mediated inhibition of motor proteins that link membra ne organelles along the secretory pathway to the cytoskeleton. This divalen t cation thus represents a new tool for studying protein secretion and memb rane dynamics along the secretory pathway. (C)2000 Academic Press.